Renal failure therapy system and method of cleaning using citric acid

ABSTRACT

A renal failure therapy system (10a, 10b) includes a dialysis fluid circuit (30) including a dialysis fluid pump (54, 58); a source (86, 90) of physiological cleaning, disinfecting, and/or decalcifying substance in fluid communication with the dialysis fluid circuit; a source (22) of purified water in fluid communication with the dialysis fluid circuit; and a logic implementer (20) in operable communication with the dialysis fluid pump (54,58), the logic implementer (20) causing the physiological cleaning, disinfecting, and/or decalcifying substance from its source (86, 90) to be added to purified water from the purified water source (22) to form a mixture and to circulate the mixture within the dialysis fluid circuit using the dialysis fluid pump (54,58) to at least one of clean, disinfect or decalcify at least a portion of the dialysis fluid circuit (30) without a subsequent rinse.

PRIORITY CLAIM

The present application is a National Phase of International ApplicationNo. PCT/EP2017/070749, filed Aug. 16, 2017, which claims priority toSwedish Application No. 1651113-1, filed Aug. 18, 2016, the entirecontents of each of which are incorporated herein by reference andrelied upon.

BACKGROUND

The present disclosure relates generally to medical systems and methods.More specifically, the present disclosure relates to renal failuretherapy systems and methods of cleaning same.

Hemodialysis (“HD”) in general uses diffusion to remove waste productsfrom a patient's blood. A diffusive gradient that occurs across thesemi-permeable dialyzer between the blood and an electrolyte dialysissolution causes diffusion. Hemofiltration (“HF”) is an alternative renalreplacement therapy that relies on a convective transport of toxins fromthe patient's blood. This therapy is accomplished by adding substitutionor replacement fluid to the extracorporeal circuit during treatment(typically ten to ninety liters of such fluid). The substitution fluidand the fluid accumulated by the patient in between treatments isultrafiltered over the course of the HF treatment, providing aconvective transport mechanism, which is particularly beneficial inremoving middle and large molecules (in hemodialysis there is a smallamount of waste removed along with the fluid gained between dialysissessions, however, the solute drag from the removal of thatultrafiltrate is typically not enough to provide convective clearance).

Hemodiafiltration (“HDF”) is a treatment modality that combinesconvective and diffusive clearances. HDF flows dialysis fluid through adialyzer, similar to standard hemodialysis, providing diffusiveclearance. In addition, substitution solution is provided directly tothe extracorporeal circuit, providing convective clearance.

The above modalities are provided by a dialysis machine. The machinesmay be provided in a center or in a patient's home. Dialysis machinesprovided in a center are used multiple times a day for multiple patientsand are therefore cleaned between treatments. There are differentprocesses for cleaning dialysis machines that use different cleaningagents. One type of cleaning agent is citric acid. Known steps of thecitric acid cleaning process include a rinsing phase in which the citricacid cleaning agent is flushed from the machine. The flushing step mayvary between fifteen and twenty minutes.

For in center dialysis in particular, time is money. While the dialysismachine is down in between treatments, a patient cannot be dialyzed.Also, downtime generally means nurse time. When dialysis treatment isrunning smoothly, the nurse does not have to attend the machineconstantly and may be off performing other tasks. Nursing time isexpensive too. There is accordingly a need to reduce downtime betweenhemodialysis treatments as much as possible.

SUMMARY

The present disclosure provides a renal failure therapy system andmethod that performs hemodialysis (“HD”), hemofiltration (“HF”),hemodiafiltration (“HDF”), peritoneal dialysis (“PD”), isolatedultrafiltration (“UF”), slow continuous ultrafiltration (“SCUF”),continuous renal replacement therapy (“CRRT”), continuous veno-venoushemodialysis (“CVVHD”), continuous veno-venous hemofiltration (“CVVH”),and continuous veno-venous hemodiafiltration (“CVVHDF”). Accordingly,“renal failure therapy” as used herein is meant to include any one, ormore, or all of the above modalities.

The present disclosure takes advantage of the fact that citric acid usedto disinfect a dialysis machine between treatments is a weak humanorganic acid. It is in fact a natural preservative/conservative and isused to add an acidic or sour taste to foods and drinks. Inbiochemistry, citric acid is important as an intermediate in the citricacid cycle, which occurs in the metabolism of higher organisms. Citricacid and citrate are related compounds. That is, at a physiologicallysafe pH, citric acid exists predominantly in an ionized form, which isknown as citrate. It is an example of a chemical equilibrium reached ina biological system. When citric acid meets blood, including the blood'sbicarbonate content, the citric acid transforms into to citrate.

In dialysis, citrate (a salt of citric acid, may be in combination withcitric acid itself) is used, inter alia, as an anticoagulant. Forexample, assuming a blood flow of 300 ml/minute, a concentration ofabout 3.5 mmol citrate may be introduced into the patient'sextracorporeal circuit at a flowrate of about 0.2 gram/minute. Calciumis added when using citrate to ensure a minimal concentration of freecalcium in the patient's bloodstream. The patient accordingly tolerates6 to 12 grams of citrate per hour using citrate anticoagulant.

Knowing that the patient may tolerate small levels of citric acid, thesystem and method of the present disclosure seek to streamline thedisinfection process between dialysis treatments, e.g., in a center,using citric acid as the disinfectant, by removing the complete flushingphase. Much of the citric acid may be drained from the system during apartial drain (e.g., ten percent to seventy-five percent (10% to 75%) oftotal dialysis fluid circuit volume) at the end of the disinfectionsequence. Another portion of the citric acid is flushed from the machineflow path during the startup of the machine for a new treatment. Thestartup of the machine from a citric acid cleaning may take 3 to 4minutes. Further, it has become more and more common to prime the lineset for the next treatment using dialysis fluid, wherein, for example,bicarbonate and A-concentrate are regulated to a proper or desired level(normally 4 to 8 minutes), during which the citric acid will be furtherflushed from the system.

In one example sequence, at the end of treatment, the used dialysisfluid in the dialysis machine is drained completely. The disinfectionsequence of the present disclosure is then commenced. First, thedialysis fluid side of the machine is filled with purified water, suchas reverse osmosis (“RO”) water. The dialysis fluid pumps are used toperform the filling. During the water filling step, citric acid is addedto the water as a disinfectant. The blood side of the machine in oneembodiment constitutes a disposable set, which is discarded betweentreatments, and is thus not part of the disinfection sequence.

The citric acid has multiple effects, one, along with hot watercleaning, is to clean the dialysis fluid circuit from precipitates ofcalcium carbonate (i.e., limestone), which is often calleddecalcification. Second, citric acid also reinforces heat disinfection,and indeed improves the heat disinfection using water only during aprescribed time and for a given temperature. For example, it has beenpublished that adding two to three percent (2% to 3%) citric acidachieves heat disinfection obtained from disinfection using pure waterbut heated to ten degrees higher. Varying heat and citric acid levelsallows the user to desirably balance disinfection effectiveness,disinfection time, and machine wear.

One suitable citric acid dry concentrate container, marketed asCleanCart®, provides 32 grams of citric acid to the water filling thedialysis fluid circuit. The dialysis fluid circuit in one embodimentholds about two to three liters of water. The water and citric acidfilling step may take, for example, one to two minutes.

In a second disinfection step, the water and citric acid mixture isheated, e.g., to a higher temperature of 60-93° C. The heater used is inone embodiment the dialysis fluid heater provided with the dialysismachine. The heating step may last approximately one to thirty minutesdepending on the heating temperature and the amount of disinfectionneeded. During the heating step, the water and citric acid arecirculated past the heater to help heat the fluid uniformly andcompletely. The circulation also helps to blend the water and citricacid.

In a third disinfection step, the heated water and citric acid solutionor mixture is circulated around the dialysis fluid circuit using thedialysis fluid pumps. The heated mixture may be pumped back and forth tocreate a washing motion and to ensure that all inner workings of thetubing and dialysis fluid components are contacted. This third cleaningstep may vary between one and thirty minutes. The dialysis machine mayor may not flush some of the water and citric acid without replacing thecleaning fluid, so that some of the citric acid is removed from thedialysis fluid circuit and is exchanged with new and heated purified,e.g., RO water. It is estimated that the exchanges remove about thirtyto seventy percent of the original concentration of citric acid.

In a fourth disinfection step, the dialysis machine performs a partialor full drain. One example of a full drain is when the machine attemptsto drain itself as much as possible, which may lead to a drain of abouteighty to ninety-five percent (80% to 95%) of all fluid within thedialysis fluid circuit. An example partial drain may then be when it isnot intended for the machine to drain completely and instead drain onlypartially, e.g., from about ten to seventy-five percent (10% to 75%)empty. The full and partial drains also serve to remove heat from thedialysis fluid circuit (assuming heat has been added via thedisinfection fluid). The dialysis fluid for the next patient needs to beat body temperature, e.g., about 37° C.

A partial drain will accordingly remove about 10% to 75% of the citricacid in the flow path. However when water and dialysis fluid is laterintroduced into the machine, the new fluid will pressurize one or moreair cushion with the fluid remaining in the machine from the partialdrain. The one or more air cushion will cause the difference in theremoval of citric acid between a full drain and a partial drain to beminimal.

Thus, by the end of the partial drain (when the air front reaches theend of the flow path, only about three (3) grams of citric acid shouldremain in the dialysis fluid circuit (assuming 32 grams of citric acidis added initially). The remaining citric acid level is accordinglyalready below the six (6) to twelve (12) grams of citrate that thepatient may tolerate using citrate anticoagulant. The limited drain maylast one or two minutes.

In a fifth step, the filling or priming of the dialysis machine for thenext patient removes much of the, e.g., three (3) grams of citric acidremaining after the limited drain. During the filling or priming for thenext patient, which may last five to ten minutes, acid and bicarbonateare added to the purified, e.g., RO, water to make dialysis solution,which is physiologically compatible with the patient's blood. Thefilling or priming step also includes exchanges to push air to drain andthereby removes about ninety percent (90%) of the three (3) grams ofcitric acid left after the limited drain. Thus, only about, e.g., 0.3gram of the original 32 grams of citric acid from the disinfectionsequence remains after filling or priming.

Charts are provided below illustrating that the effect of citric acid onpH while forming dialysis fluid is overcome in a matter of minutes. Forboth bicarbonate and acetate type of dialysis fluid preparation, a“green fluid path” (meaning it is OK to proceed with therapy) is reachedwithin minutes.

Of the 0.3 gram of citric acid remaining after filling or priming, itmay be assumed that only half of it, e.g., about 0.15 to 0.2 gram,resides on the upstream or fresh dialysis fluid side of the dialysisfluid circuit. That is, the other part of the 0.3 gram of citric acid ispresumed to reside on the downstream or used fluid side of the dialysisfluid circuit. Dialysis fluid residing on the used fluid side of thedialysis fluid circuit cannot reach the patient and will instead beflushed to drain. Moreover, of the, e.g., 0.15 to 0.2 gram of citricacid residing on the fresh fluid side of the dialysis fluid circuit,only a portion will reach the patient. Some of the, e.g., 0.15 to 0.2gram may be ultrafiltered into substitution fluid which is delivereddirectly to the blood circuit. Some of the, e.g., 0.15 to 0.2 gram ofcitric acid may osmose across the dialyzer membranes into the bloodcircuit. Some of the, e.g., 0.15 to 0.2 gram of citric acid however willflow through the dialysis fluid compartment, into the used fluid side ofthe dialysis fluid circuit, to drain. In the end, a very small,negligible amount of citric acid is delivered to the patient.

Various alternatives to the above-described sequence are contemplated.For example, it may be possible to shorten or even eliminate thecleaning or limited drain steps. It may also be possible to raise theinitial concentration of citric acid, e.g., to 50 grams or so, and use ashorter, third cleaning step, so that the overall cleaning level remainsapproximately the same.

In light of the technical features set forth herein, and withoutlimitation, in a first aspect, a renal failure therapy system includes:a dialysis fluid circuit including a dialysis fluid pump; a source ofphysiological cleaning, disinfecting, and/or decalcifying substance influid communication with the dialysis fluid circuit; a source ofpurified water in fluid communication with the dialysis fluid circuit;and a logic implementer in operable communication with the dialysisfluid pump, the logic implementer programmed to cause the physiologicalcleaning, disinfecting, and/or decalcifying substance to be added fromits source to purified water from the purified water source to form amixture and to circulate the mixture within the dialysis fluid circuitusing the dialysis fluid pump to at least one of clean, disinfect ordecalcify at least a portion of the dialysis fluid circuit without asubsequent rinse.

In a second aspect, which may be used with any other aspect describedherein unless specified otherwise, the physiological cleaning,disinfecting, and/or decalcifying substance includes an acid.

In a third aspect, which may be used with the second aspect incombination with any other aspect described herein unless specifiedotherwise, the acid is at least partially citric acid.

In a fourth aspect, which may be used with any other aspect describedherein unless specified otherwise, the physiological cleaning,disinfecting, and/or decalcifying substance includes citric acid incombination with a physiologically safe substance.

In a fifth aspect, which may be used with any other aspect describedherein unless specified otherwise, a filling procedure for a subsequenttreatment is used to remove a portion of the mixture to drain.

In a sixth aspect, which may be used with the fifth aspect incombination with any other aspect described herein unless specifiedotherwise, the filling procedure involves the introduction of abicarbonate substance from a source that neutralizes the physiologicalcleaning, disinfecting, and/or decalcifying substance.

In a seventh aspect, which may be used with the fifth aspect incombination with any other aspect described herein unless specifiedotherwise, the filling procedure removes at least one percent of anoriginal amount of the physiological cleaning, disinfecting, and/ordecalcifying substance.

In an eighth aspect, which may be used with the fifth aspect incombination with any other aspect described herein unless specifiedotherwise, the renal failure therapy system includes a heater, the logicimplementer programmed to control the heater during the fillingprocedure to heat a filling fluid to a temperature below 35° C. to coolthe dialysis fluid circuit.

In a ninth aspect, which may be used with the eighth aspect and anyother aspect described herein unless specified otherwise, the logicimplementer further programmed to cause the heater to heat the mixturewhile at least one of cleaning, disinfecting or decalcifying the atleast a portion of the dialysis fluid circuit.

In a tenth aspect, which may be used with any other aspect describedherein unless specified otherwise, the logic implementer in a drainsequence programmed to remove a portion of the mixture to drain.

In an eleventh aspect, which may be used with the tenth aspect incombination with any other aspect described herein unless specifiedotherwise, the drain sequence is a partial drain sequence.

In a twelfth aspect, which may be used with any other aspect describedherein unless specified otherwise, wherein the logic implementer isprogrammed to cause the physiological cleaning, disinfecting, and/ordecalcifying substance to be added from its source to purified waterfrom the purified water source to form the mixture and to circulate themixture within the dialysis fluid circuit using the dialysis fluid pumpto at least one of clean, disinfect or decalcify at least a portion ofthe dialysis fluid circuit without a subsequent rinse or a subsequentdrain.

In a thirteenth aspect, which may be used with the fifth aspect incombination with any other aspect described herein unless specifiedotherwise, the renal failure therapy system includes a source ofconcentrate in fluid communication with the dialysis fluid circuit, andwherein the logic implementer is programmed to cause concentrate fromthe concentrate source to be mixed with the remaining mixture during thefilling procedure to form dialysis fluid for the subsequent treatment.

In a fourteenth aspect, which may be used with any other aspectdescribed herein unless specified otherwise, the renal failure therapysystem includes a blood set, wherein the blood set is removed while thedialysis fluid pump at least one of cleans, disinfects or decalcifiesthe at least a portion of the dialysis fluid circuit without asubsequent rinse.

In a fifteenth aspect, which may be used with the fifth aspect and anyother aspect described herein unless specified otherwise, a renalfailure therapy machine is operable with a source of physiologicalcleaning, disinfecting, and/or decalcifying substance and a source ofpurified water, the machine including: a dialysis fluid circuitincluding a dialysis fluid pump, the dialysis fluid circuit configuredto pump from the physiological cleaning, disinfecting, and/ordecalcifying substance source and the purified water source; and a logicimplementer in operable communication with the dialysis fluid pump, thelogic implementer programmed to cause: (i) the physiological cleaning,disinfecting, and/or decalcifying substance from its source to be addedto purified water from the purified water source to form a mixture andto circulate the mixture within the dialysis fluid circuit using thedialysis fluid pump to at least one of clean, disinfect or decalcify atleast a portion of the dialysis fluid circuit after a first treatment,(ii) a portion of the mixture to be drained in a drain sequence, and(iii) a filling procedure for a second treatment to begin with themixture remaining in the dialysis fluid circuit, the filling procedurerelied upon to reduce the mixture remaining to a lower level.

In a sixteenth aspect, which may be used with the fifteenth aspect incombination with any other aspect described herein unless specifiedotherwise, the logic implementer is programmed to circulate the mixturewithin the dialysis fluid circuit from about one (1) to about thirty(30) minutes.

In a seventeenth aspect, which may be used with the fifteenth aspect incombination with any other aspect described herein unless specifiedotherwise, wherein during (iii) at least one percent of an originalamount of the physiological cleaning, disinfecting, and/or decalcifyingsubstance is removed.

In an eighteenth aspect, which may be used with the fifteenth aspect incombination with any other aspect described herein unless specifiedotherwise, wherein during (iii) a bicarbonate substance from a source isprovided, which neutralizes the physiological cleaning, disinfecting,and/or decalcifying substance.

In a nineteenth aspect, which may be used with any other aspectdescribed herein unless specified otherwise, a cleaning method for arenal failure therapy machine includes: pumping purified water and aphysiological cleaning, disinfecting, and/or decalcifying substance toform a mixture; pumping the mixture to at least one of clean, disinfector decalcify at least a portion of a dialysis fluid circuit; draining aportion of the mixture from the dialysis fluid circuit; and moving to asubsequent treatment without performing a rinse.

In a twentieth aspect, which may be used with the nineteenth aspect incombination with any other aspect described herein unless specifiedotherwise, wherein the drained portion of the mixture is a firstportion, and wherein moving to the subsequent treatment includesperforming a filling procedure that drains a second portion of themixture.

In a twenty-first aspect, which may be used with the nineteenth aspectin combination with any other aspect described herein unless specifiedotherwise, wherein draining a portion of the mixture from the dialysisfluid circuit includes trapping air in the dialysis fluid circuit.

In a twenty-second aspect, which may be used with any other aspectdescribed herein unless specified otherwise, the system includes atleast one of (i) a keyed connector for the source of physiologicalcleaning, disinfecting, and/or decalcifying substance and a mating keyedconnector for the dialysis fluid circuit, or (ii) a marking associatedwith the source of physiological cleaning, disinfecting, and/ordecalcifying substance and a scanner, reader, RFID reader, or camera incommunication with logic implementer for reading the marking, upon whichlogic implementer may allow or confirm the circulating of the mixturewithout the subsequent rinse.

In a twenty-third aspect, which may be used with any other aspectdescribed herein unless specified otherwise, the dialysis fluid circuitincludes a disinfection recirculation loop and an air separation chamberlocated within the loop, the air separation chamber increasing at leastone of flowrate and heating efficiency of the physiological cleaning,disinfecting, and/or decalcifying substance flowing within thedisinfection recirculation loop.

In a twenty-fourth aspect, any of the features, functionality andalternatives described in connection with any one or more of FIG. 1A to7 may be combined with any of the features, functionality andalternatives described in connection with any of the other one or moreof FIG. 1A to 7.

In light of the above aspects and the teachings herein, it is thereforean advantage of the present disclosure to provide a hemodialysis,hemofiltration or hemodiafiltration system and method that reducesmachine downtime.

It is another advantage of the present disclosure to provide ahemodialysis, hemofiltration or hemodiafiltration system and method thatreduces nurse interaction.

It is a further advantage of the present disclosure to provide ahemodialysis, hemofiltration or hemodiafiltration system and method thatreduces treatment cost.

Moreover, it is an advantage of the present disclosure to provide ahemodialysis, hemofiltration or hemodiafiltration system and method thatuses an environmentally safe disinfecting agent.

The advantages discussed herein may be found in one, or some, andperhaps not all of the embodiments disclosed herein. Additional featuresand advantages of the present invention are described in, and will beapparent from, the following Detailed Description of the Invention andthe figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a schematic illustration of one embodiment of a renal therapysystem including a citric acid liquid source, which may be used with thedisinfection sequence or method of the present disclosure.

FIG. 1B is a schematic illustration of one embodiment of a renal failuretherapy system including a dry powder citric acid cartridge, which maybe used with the disinfection sequence or method of the presentdisclosure.

FIG. 2 is an elevation view of one embodiment for an air separationdevice placed at the end of a drain line as part of a disinfectionrecirculation loop.

FIG. 3 is an elevation cross-sectional view of one embodiment of ahemodialysis blood set, which may be used with the disinfection sequenceor method of the present disclosure

FIG. 4 is a process flow diagram illustrating one embodiment of adisinfection sequence of the present disclosure, which may be automatedusing the example systems of FIGS. 1A and 1B.

FIG. 5 is an example timeline schematic further illustrating the processflow diagram of FIG. 4.

FIG. 6 is a chart illustrating one example of pH balancing or recoveryduring priming using bicarbonate concentrate with residual citric acidand purified water.

FIG. 7 is a chart illustrating one example of pH balancing or recoveryduring priming using acetate concentrate with residual citric acid andpurified water.

DETAILED DESCRIPTION

Referring now to the drawings and in particular to FIGS. 1A and 1B,embodiments of the system of the present disclosure are illustrated bysystems 10 a and 10 b. Systems 10 a and 10 b each include a machine 12having a housing. Machine 12 holds the contents of a dialysis fluidcircuit 30 described in detail below. Machine 12 also supports a userinterface 14, which allows a nurse or other operator to interact withsystems 10 a and 10 b. User interface 14 may have a monitor screenoperable with a touch screen overlay, electromechanical buttons, e.g.,membrane switches, or a combination of both. User interface 14 is inelectrical communication with at least one processor 16 and at least onememory 18. At least one processor 16 and at least one memory 18 alsoelectronically interact with, and where appropriate, control the pumps,valves and sensors described herein, e.g., those of dialysis fluidcircuit 30. At least one processor 16 and at least one memory 18 arereferred to collectively herein as a logic implementer 20. The dashedlines extending from logic implementer 20 lead to pumps, valves,sensors, the heater and other electrical equipment, as indicated by likedashed lines leading from the pumps, valves, sensors, heater, etc.

Dialysis fluid circuit 30 includes a purified water line 32, anA-concentrate line 34 and a bicarbonate B-concentrate line 36. Purifiedwater line 32 receives purified water from a purified water device orsource 22. The water may be purified using any one or more process, suchas, reverse osmosis, carbon filtering, ultraviolet radiation,electrodeionization (“EDI”), and/or ultrafiltering. One suitable deviceor source 22 for purifying the water is marketed as a WRO 300 H™ waterpurification machine.

An A-concentrate pump 38, such as a peristaltic or piston pump, pumpsA-concentrate from an A-concentrate source 24 into purified water line32 via A-concentrate line 34. Conductivity cell 40 measures theconductive effect of the A-concentrate on the purified water, sends asignal to logic implementer 20, which uses the signal to properlyproportion the A-concentrate by controlling A-concentrate pump 38. TheA-conductivity signal is temperature compensated via a reading fromtemperature sensor 42.

A B-concentrate pump 44, such as a peristaltic or piston pump, pumpsB-concentrate, e.g., a bicarbonate substance, from a B-concentratesource 26 into purified water line 32 via B-concentrate line 36.Conductivity cell 46 measures the conductive effect of the B-concentrateon the purified water/A-concentrate mixture, sends a signal to logicimplementer 20, which uses the signal to properly proportion theB-concentrate by controlling B-concentrate pump 44. The B-conductivitysignal is also temperature compensated via a reading from temperaturesensor 48.

An expansion tank 50 deaerates the purified water prior to receiving theconcentrates, removing bubbles from the water, which has been degassedin a chamber 51 via a degassing pump 53, located below expansion tank50. A heater 52 controlled by logic implementer 20 heats the purifiedwater for treatment to body temperature, e.g., 37° C. The fluid exitingconductivity cell 46 is therefore freshly prepared dialysis fluid,properly degassed and heated, and suitable for sending to a dialyzer fortreatment. A fresh dialysis fluid pump 54, such as a gear pump, deliversthe fresh dialysis fluid to a dialyzer (see FIG. 3). Logic implementer20 controls fresh dialysis fluid pump 54 to deliver fresh dialysis fluidto the dialyzer at a specified flowrate.

A used dialysis fluid pump 58 located along drain line 56 pumps useddialysis fluid from the dialyzer to a drain 60. Logic implementer 20controls used dialysis fluid pump 58 to pull used dialysis fluid fromthe dialyzer at a specified flowrate. A pressure sensor 62 senses thepressure of spent dialysis fluid within drain line 56 and sends acorresponding pressure signal to logic implementer 20. A blood leakdetector 64, such as an optical detector, looks for the presence ofblood in drain line, e.g., to detect if a dialyzer membrane has a tearor leak. A heat exchanger 66 recoups heat from the used dialysis fluidexiting dialysis fluid circuit 30 to drain 60, preheating the purifiedwater traveling towards heater 52 to conserve energy.

UF system 96 monitors the flowrate of fresh dialysis fluid flowing todialyzer 102 (and/or as substitution fluid flowing directly to the bloodset (FIG. 3)) and used fluid flowing from the dialyzer. UF system 96includes fresh and used flow sensors as part of a UF System Control,which sends signals to logic implementer 20 indicative of the fresh andused dialysis fluid flowrate, respectively. Logic implementer 20 usesthe signals to set used dialysis fluid pump 58 to pump faster than freshdialysis fluid pump 54 by a predetermined amount to remove a prescribedamount of ultrafiltration (“UF”) from the patient over the course oftreatment. A second set of fresh and used flow sensors may be providedas part of UF System Protective, which are redundant sensors that ensureUF system 96 is functioning properly.

A bypass line 68 allows fresh dialysis fluid to flow from fresh dialysisfluid line 70 to drain line 56 without contacting the dialyzer. A freshdialysis fluid tube 72 extends from the housing of machine 12 andcarries fresh dialysis fluid from fresh dialysis fluid line 70 to thedialyzer. A used dialysis fluid tube 74 also extends from the housing ofmachine 12 and carries used dialysis fluid from the dialyzer to drainline 56.

During disinfection, the distal end 72 a of fresh dialysis fluid tube 72is not connected to the dialyzer and is instead plugged into machine 12,so as to sealingly communicate with a fresh disinfection recirculationline 76, which feeds into purified water line 32 upstream of heatexchanger 66. Disinfection fluid may therefore be circulated throughpurified water line 32, fresh dialysis fluid line 70, fresh dialysisfluid tube 72 and fresh disinfection recirculation line 76.

Likewise, during disinfection the distal end 74 a of used dialysis fluidtube 74 is not connected to the dialyzer and is instead plugged intomachine 12, so as to sealingly communicate with used disinfectionrecirculation line 78, which feeds drain line 56 downstream of useddialysis fluid pump 58. Disinfection fluid may therefore be circulatedthrough drain line 56, used dialysis fluid tube 74 and used disinfectionrecirculation line 78.

Also during disinfection, A-concentrate supply 24 and B-concentratesupply 26 are disconnected from dialysis fluid circuit 30 as illustratedin FIGS. 1A and 1B and plugged into machine 12. A shunt line 80 isplaced instead at the A-concentrate connection to machine 12, fluidlyconnecting the A-concentrate line 34 to a water supply branch line 82.Disinfection fluid may therefore be circulated through A-concentrateline 34, shunt line 80 and water supply branch line 82.

The differences between system 10 a of FIG. 1A and system 10 b of FIG.1B are that in system 10 a of FIG. 1A, a second shunt line 84 is placedat the B-concentrate connection to machine 12, fluidly connecting theB-concentrate line 36 to water supply branch line 82. Disinfection fluidmay therefore be circulated through B-concentrate line 36, second shuntline 84 and water supply branch line 82. Also in FIG. 1A, citric acidconcentrate in liquid form is provided from a source 86 via a citricacid supply line 88 to water supply branch line 82. A- or B-concentratepump 38 or 44 under control of logic implementer 20 may meter a desiredamount of liquid citric acid concentrate from supply 86 into the freshrecirculation loop, including fresh disinfection recirculation line 76,using water supply branch line 82. Bypass line 68 may be opened to allowthe citric acid disinfectant to reach used recirculation loop includingused disinfection recirculation line 78. Thus, the entire dialysis fluidcircuit 30 may be disinfected. Heat from heater 52 is also used fordisinfection in one embodiment.

Although not illustrated, systems 10 a and 10 b may place an air traptype structure at the junction between used disinfection recirculationline 78 and drain line 56, just to the right of drain valve 92 d. Theair trap type structure separates air from whatever liquid is flowingthrough drain line 56, so that the air may be pushed to drain 60,leaving degassed liquid to flow back through used disinfectionrecirculation line 78.

In system 10 b of FIG. 1B, liquid citric acid concentrate source 86 andcitric acid supply line 88 are not used. Instead, a flow-through dryconcentrate source or cartridge 90, such as the CleanCart® cartridge, isinserted into second shunt line 84 and is thus placed in fluidcommunication with water supply branch line 82 and B-concentrate line36. B-concentrate pump 44 pulls purified water through water supplybranch line 82, dry concentrate source or cartridge 90, second shuntline 84, and B-concentrate line 36 into the fresh recirculation loopincluding fresh disinfection recirculation line 76 and the usedrecirculation loop including used disinfection recirculation line 78 viaopened bypass line 68. Thus, the entire dialysis fluid circuit 30 insystem 10 b may be disinfected. Heat from heater 52 is also used fordisinfection in system 10 b.

In system 10 b, the dry concentrate is provided in an amount appropriatefor the volume of dialysis fluid circuit 30, including shunt line 84 anddialysis fluid tubes 72 and 74, assuming that all of the powder fromsource 90 is dissolved fully into the purified water. In an embodiment,fully dissolving all the powder from the CleanCart® cartridge introduces32 grams of citric acid into dialysis fluid circuit 30. The CleanCart®cartridge contains citric acid anhydrate powder, and is used in oneembodiment in combination with heat disinfection to both decalcify anddisinfect the dialysis fluid circuit simultaneously. The resultingcitric acid solution while circulated removes precipitates of calciumand magnesium carbonates.

Systems 10 a and 10 b of FIGS. 1A and 1B each provide plural valves 92(collectively referring to valves 92 a to 92 f) under the control oflogic implementer 20 to selectively control a filling or primingprocedure before treatment, the dialysis treatment, disinfection aftertreatment, and other sequences and procedures involved with systems 10 aand 10 b. In particular, valve 92 a selectively opens and closes bypassline 68, e.g., to allow disinfection fluid to flow from the freshdialysis fluid circulation loop to the used dialysis fluid circulationloop. Valve 92 b selectively opens and closes fresh disinfectionrecirculation line 76. Valve 92 c selectively opens and closes useddisinfection recirculation line 78. Valve 92 d selectively opens andcloses drain line 56 to drain 60, which is an important pathway for thecitric acid disinfection sequence described in more detail below. Valve92 e selectively opens and closes purified water line 32 to purifiedwater source 22, which is also an important pathway for the citric aciddisinfection sequence described in more detail below. Valve 92 f forsystem 10 a (not system 10 b) selectively opens and closes water supplybranch line 82 to citric acid source 86.

It should be appreciated that the dialysis fluid circuits 30 of FIGS. 1Aand 1B are simplified and may include other structure and functionalitynot illustrated. Also, dialysis fluid circuits 30 of FIGS. 1A and 1Billustrate a hemodialysis (“HD”) pathway. It is expressly contemplatedto provide one or more ultrafilter in fresh dialysis fluid line 70 tocreate substitution fluid for hemofiltration (“HF”). It is alsoexpressly contemplated to provide one or more ultrafilter in one or moreline(s) branching off of fresh dialysis fluid line 70 to createsubstitution fluid, in addition to the fresh dialysis fluid in line 70,for hemodiafiltration (“HDF”). In each case, the disinfection sequencesdescribed below would also reach and disinfect any additional oralternative tubing, filters, pumps, valves and other associatedstructure.

Referring now to FIG. 2, in an alternative embodiment, either one orboth of systems 10 a and 10 b of FIGS. 1A and 1B may replace (or addadjacent to) its drain valve 92 d with an air separation chamber 150.Air separation chamber 150 is made of a suitable medical grade plasticor metal in various embodiments. Air separation chamber 150 includes achamber housing 152, a liquid/air inlet 154, a liquid/air outlet 156,and a pure (or almost pure) liquid outlet 158. The liquid at varioustimes may be used dialysis fluid, purified water, or heated water with aphysiologically safe cleaning agent as described herein, such as citricacid. As used herein, a physiologically safe substance may be one thatin its current or in a diluted form is safe for injection into apatient's bloodstream.

Liquid/air inlet 154 and liquid/air outlet 156 as illustrated in FIG. 2splice into drain line 56 of systems 10 a and 10 b of FIGS. 1A and 1B.Liquid outlet 158 as illustrated in FIG. 2 connects to used disinfectionrecirculation line 78 of systems 10 a and 10 b of FIGS. 1A and 1B. Ineffect, air separation chamber 150 replaces the tee in FIGS. 1A and 1B,where used disinfection recirculation line 78 meets with drain line 56line just upstream of drain valve 92 d. Again, air separation chamber150 may or may not take the place of drain valve 92 d.

Air separation chamber 150 removes air from used dialysis fluidcirculation loop, which includes drain line 56 and used disinfectionrecirculation line 78. The air is removed primarily via buoyancy forcesas illustrated in FIG. 2. Air separation chamber 150 may employ bafflesor other structures within chamber housing 152 if desired to helpseparate air from whatever type of liquid is present. The removal of airhelps to fill the disinfection recirculation loop 56, 78 with less airand consequently more fluid to improve flowrate, which in turn helps theefficiency of cleaning, disinfecting and decalcifying.

The volume of chamber housing 152 of air separation chamber 150 helps tofill lines 56 and 78 of the recirculation loop 56, 78 because waterfills chamber housing 152 instead of flowing to drain 60, trapping heat,and thereby allowing the temperature of the cleaning, disinfecting anddecalcifying fluid to rise more quickly. Also, as the liquid levelwithin chamber housing 152 rises, air is released from the fluid todrain, such that the cleaning, disinfecting and decalcifying fluid tendsto become dearated during the filling of disinfection recirculation loop56, 78. Again, improved heating efficiency and dearated cleaning,disinfecting and decalcifying fluid help to improve the overallefficiency of the cleaning, disinfecting and decalcifying. Moreover,electromechanical drain valve 92 d may be removed from systems 10 a and10 b, decreasing cost and overall component wear.

In an embodiment, a liquid level sensor (not illustrated), such as anultrasonic, capacitive, inductive sensor or optical sensor, ispositioned adjacent chamber housing 152 of air separation chamber 150,such that the sensor may sense when chamber housing 152 is full oralmost full. The liquid level sensor is in logic communication withlogic implementer 20 and changes output level or state when the liquidlevel transitions from not full to full (or almost full) and vice versa.Logic implementer 20 uses the level sensor signal to toggle bypass valve92 a to (i) open to fill chamber housing 152 until the level sensorreads full (or almost full) and (ii) close when chamber housing 152 isfull (or almost full) until the liquid level falls below the liquidlevel sensor, changing its output again to reopen bypass valve 92 a. Inthis manner, disinfection fluid does not flow out of chamber housing 152and is therefore not wasted to drain 60.

Referring now to FIG. 3, blood set 100 illustrates one embodiment of ablood set that may be used with either system 10 a or 10 b. Blood set100 includes a dialyzer 102 having many hollow fiber semi-permeablemembranes 104, which separate dialyzer 102 into a blood compartment anda dialysis fluid compartment. The dialysis fluid compartment duringtreatment is placed in fluid communication with distal end 72 a of freshdialysis fluid tube 72 and distal end 74 a of used dialysis fluid tube74. FIGS. 1A and 1B illustrate that during disinfection and priming,distal ends 72 a and 74 a are instead plugged sealingly intodisinfection recirculation lines 76 and 78, respectively. It should beappreciated that for HF, replacement fluid flows from a substitutionline (not illustrated) directly to one or both arterial line 106 andvenous line 108 of blood set 100, while fresh dialysis fluid line 70 isoccluded so that fresh dialysis fluid does not flow to dialyzer 102. ForHDF, replacement fluid flows from the substitution line (notillustrated) directly to one or both arterial line 106 and venous line108 of blood set 100, while fresh dialysis fluid line 70 is opened sothat fresh dialysis fluid flows additionally to dialyzer 102.

Arterial pressure pod 110, located upstream of blood pump 120, enablesarterial line pressure to be measured, while venous line 108 includes avenous pressure pod 112, enabling venous line pressure to be measured.Pressure pods 110 and 112 operate with blood pressure sensors (not seen)mounted on the housing of machine 12, which send arterial and venouspressure signals, respectively, to logic implementer 20. Venous line 108includes a venous drip chamber 114, which removes air from the patient'sblood before the blood is returned to patient 116.

Arterial line 106 of blood set 100 includes a portion operable withblood pump 120, which is under the control of logic implementer 20 topump blood at a desired flowrate. Systems 10 a and 10 b also providemultiple blood side electronic devices that send signals to and/orreceive commands from logic implementer 20. For example, logicimplementer 20 commands pinch clamps 122 a and 122 b to selectively openor close arterial line 106 and venous line 108, respectively. A bloodvolume sensor (“BVS”) 124 is located along arterial line 106 upstream ofblood pump 120. Air detector 126 looks for air in venous blood line 108.Air detector 126 looks for air in venous blood line 108.

Referring now to FIG. 4, one embodiment of a sequence or method of thepresent disclosure is illustrated by method 200. Method 200 may bestored on one or more memory device 18 of logic implementer 20. One ormore processor 16 of logic implementer 20 runs method 200 automaticallyin one embodiment at the end of treatment. At step 202, method 200begins. At step 204, system 10 a or 10 b performs a renal failuretherapy treatment, such as hemodialysis (“HD”), hemofiltration (“HF”) orhemodiafiltration (“HDF”). The dialysis fluid is a physiological fluidthat will act as a nutrition solution for many types of bacteria.Bacteria may enter dialysis fluid circuit 30 and together with thedialysis fluid begin to multiply. Also, dialysis fluid is not a stablesolution and over time some precipitation will occur within dialysisfluid circuit 30. Accordingly, the dialysis fluid circuit 30 and inparticular drain line 56 (due to the risk of cross-contamination frompatient to patient) needs to be disinfected regularly to ensure that noexcessive bacterial growth starts in the machines of systems 10 a or 10b. At the end of step 204, blood set 100 and dialyzer 102 may be removedfrom system 10 a or 10 b as has been discussed herein.

At step 206, logic implementer 20 causes fresh dialysis fluid pump 54and used dialysis fluid pump 58 to send all residual fresh and useddialysis fluid and/or substitution fluid and blood filtrated fluidwithin dialysis fluid circuit 30 to drain via drain line 56. If purehemodialysis is performed, dialysis fluid pumps 54 and 58 pump residualfresh and used dialysis fluid to drain. If pure hemofiltration isperformed, pumps 54 and 58 pump residual fresh substitution fluid andblood filtrated fluid to drain. If hemodiafiltration is performed, pumps54 and 58 pump residual fresh and used dialysis fluid and freshsubstitution fluid and blood filtrated fluid to drain. In any case,dialysis fluid circuit 30 may be essentially dry after step 206 or bepartially drained as discussed above.

At step 208, logic implementer 20 adds citric acid to purified water indialysis circuit 30. As discussed above, purified water source 22 maypurify the water using any one or more process, such as, reverseosmosis, carbon filtering, ultraviolet radiation, electrodeionization(“EDI”), and/or ultrafiltering. In one embodiment, citric acid isblended first in the fresh recirculation loop where valve 92 a isclosed, valves 92 b and 92 e are opened, allowing citric acid and waterto blend in fresh dialysis fluid line 70 and fresh disinfectionrecirculation line 76. The blended citric acid/water is then introducedinto the used recirculation loop including drain line 56 and useddisinfection recirculation line 78 by opening valve 92 a.

For example, in system 10 a of FIG. 1A, concentrate pump 38 or 44 maypull liquid citric acid concentrate from source 86, through branch waterline 82, a shunt line 80 or 84, and A-concentrate line 34 orB-concentrate line 36, into purified water line 32, while fresh dialysisfluid pump 54, with bypass valve 92 a closed, circulates the mixturewithin fresh dialysis fluid line 70 and fresh disinfection recirculationline 76. Then, the blended citric acid/water is introduced into the usedrecirculation loop including drain line 56 and used disinfectionrecirculation line 78 by opening valve 92 a.

In another example using system 10 b of FIG. 1B, B-concentrate pump 44may pull purified water through branch water line 82 and dry powdercitric acid cartridge 90, through B-concentrate line 36, into purifiedwater line 32/dialysis fluid line 70, while fresh dialysis fluid pump54, with bypass valve 92 a closed, circulates the mixture within freshdialysis fluid line 70 and fresh disinfection recirculation line 76.Then, the blended citric acid/water is introduced into the usedrecirculation loop including drain line 56 and used disinfectionrecirculation line 78 by opening valve 92 a. Again, one suitable drypowder citric acid cartridge 90 is marketed under the trade nameCleanCart®.

When valve 92 a is opened to allow the blended citric acid and purifiedwater into used recirculation loop, including drain line 56 and useddisinfection recirculation line 78, additional water is pulled frompurified water source 22 to fill the additional volume of the usedrecirculation loop. The additional purified water dilutes the citricacid concentration.

Following the example of system 10 b, dialysis fluid pumps 54 and 58circulate the purified water through dry concentrate cartridge 90 untilall or most all of the citric acid concentrate powder dissolved into thepurified water. The CleanCart® concentrate cartridge dissolves about 32grams of citric acid into the purified water. It should be appreciatedhowever that citric acid concentrates providing more or less than 32grams of citric acid are contemplated and within the scope of thepresent disclosure.

In the example of system 10 a, a liquid citric acid concentrate source86 is used instead of the dry powder concentrate. Here, a jug orcontainer 86 of liquid citric acid concentrate is placed in fluidcommunication with dialysis fluid circuit 30 and in particular theconcentrate and dialysis fluid pumps 38, 44, 54 and 58 of same. Thepumps under control of logic implementer 20 may pump all or most all, oralternatively a desired volume, of the liquid citric acid concentratefrom the source 86 into the purified water to achieve a mixture having adesired citric acid in purified water concentration, e.g., a dilutedcitric solution in the range between 0.5% and 10% citric acid, dependingon the surface area needing disinfection and decalcification. The 32grams of citric acid provided by the CleanCart® concentrate cartridge ismerely one example.

The process of filling dialysis fluid circuit 30 with water and citricacid may take from about one to about two minutes.

At step 210, logic implementer 20 commands heater 52 to heat the fluidmixture as it is circulated throughout dialysis fluid circuit 30. In oneembodiment, logic implementer causes heater 52 to heat the citric acidsolution or mixture to a desired temperature, such as 93° C. Theinputted temperature will depend upon the altitude at which machine 12is located because the boiling point of the fluid mixture lowers as theelevation rises. Also, the addition of the physiologically safe cleaningagent, such as citrate, allows the desired temperature to be lowered,e.g., by 10° C. Heater 52 is in one embodiment an inline resistanceheater. Heating step 210 may take about five to ten minutes in oneembodiment, or even up to twenty minutes depending upon the size ofheater 52.

At step 212, logic implementer 20 causes dialysis fluid or dialysisfluid pumps 54 and 58 with bypass valve 92 a open to recirculate theheated, fully concentrated citric acid mixture throughout dialysis fluidcircuit. Pumps 54 and 58 are operated at a high and perhaps maximumflowrate to obtain a more turbulent flow. The turbulent flow createsfriction against the walls of the tubing and components to increasecleaning, including increased mechanical pressure on calcium andmagnesium carbonate deposits as well as bacteria, which may try to hidein slots or behind biofilms. The citric acid disinfectant and the heatprovide a two-pronged cleaning technique. The circulation and cleaningof step 212 may last from about one (1) to thirty (30) minutes. Duringrecirculation, heat exchanger 66 acts as a heater for the disinfectionrecirculation circuit 56/78 portion of dialysis fluid circuit 30, whichis pumped by used dialysis fluid pump 58. In the other portion ofdialysis fluid circuit 30 pumped by fresh dialysis fluid pump 54, heater52 along with logic implementer 20 and temperature sensor 42 control thetemperature at sensor 42 to a desired temperature. In this way, thetemperature of the disinfection recirculation circuit 56/78 portion ofdialysis fluid circuit that used dialysis fluid pump 58 serves is closeto the temperature of the fluid mixture in the portion of dialysis fluidcircuit 30 that fresh dialysis fluid pump 54 serves.

At step 214, logic implementer 20 causes used dialysis fluid pump 58,with drain valve 92 d open, to perform a limited or partial drain. Thelimited or partial drain may last about one (1) or two (2) minutes andremove about ten percent to seventy-five percent (10% to 75%) of thevolume of fluid in dialysis fluid circuit 30 to drain 60. As discussedabove, the partial drain creates one or more air slug or pillow withindialysis fluid circuit 30, such that the partial drain removes citricacid from the disinfecting solution or mixture by sending ninety toninety-five percent (90%-95%) of the citric acid solution to drain 60.The partial drain is therefore almost as effective as a full drain interms of how much citric acid is flushed. In an embodiment, at the endof the partial or limited drain step 214, approximately all but three(3) grams of the original 32 grams, or approximately 90%, of the citrichas been removed from dialysis fluid circuit 30.

At step 216, logic implementer decides if there is another treatment forthe day. If another treatment is to be performed as illustrated at step218, a filling or priming step for the next treatment is performed.Here, logic implementer 20 of system 10 a or 10 b closes disinfectionrecirculation valve 92 c, opens drain valve 92 d and purified watervalve 92 e, and runs fresh dialysis fluid pump 54 to pull purified waterfrom source 22 to replace the volume of disinfecting fluid lost via thepartial drain at step 214 and to purge systems 10 a and 10 b of air.Logic implementer then runs A and B-concentrate pumps 38 and 44 to addA- and B-concentrates from sources 24 and 26, respectively, to formdialysis fluid.

Filling or priming step 218 fills the dialysis fluid circuit 30. Whenfilling dialysis fluid circuit 30 in one embodiment, logic implementer20 causes purified water from source 22 to flow from the beginning ofthe machine at source 22 to its end at drain 60. The purified water flowcauses remaining pockets of citric acid cleaning solution and air to beflushed to drain 60. A- and B-concentrates are then added to formdialysis fluid. To clean fresh dialysis fluid tube 72, and to preventrecirculation of citric acid from tube 72 into clean water at valve 92e, logic implementer 20 may cause used dialysis fluid pump 58 to suckthe purified water through bypass line 68, fresh dialysis fluid line 70and fresh dialysis fluid tube 72.

The first dialysis fluid to reach drain 60 will therefore be blendedwith a relatively high degree of the citric acid. But dialysis fluidduring filling or priming will quickly rid the machine of remainingcitric acid solution, e.g., within a liter or less of dialysis fluidflushed to drain 60. In an embodiment, the volume of each filling orpriming exchange is about one to three liters, such that at the end offilling or priming step 216, well over 99% of the original amount ofcitric acid has been removed from system 10. Where an original 32 gramsof citric acid is used, less than a gram, e.g., 0.3 gram, of citric acidmay remain.

The timeline of FIG. 5 shows an example where filling or priming step218 takes the citric acid level from 3 grams to 0.3 grams, removing 2.7grams. 2.7 grams out of the original 32 grams is about 8.4%. It iscontemplated for filling or priming step 218 to remove at least onepercent of the original citric acid or other physiological cleaning,disinfecting, and/or decalcifying substance, up to 10% or more dependingupon how much physiological cleaning, disinfecting, and/or decalcifyingsubstance remains at the beginning of filling or priming step 218.

At the end of filling or priming step 218, half of the approximately 0.3gram of citric acid will reside on the fresh dialysis fluid side ofdialyzer 102, while the other half of the approximately 0.3 gram ofcitric acid will reside on the used side of the dialyzer. The 0.15 gramof citric acid residing on the used side will be sent to drain oncetreatment starts and has no chance of reaching the patient. Of the 0.15gram of citric acid residing on the fresh dialysis fluid side ofdialyzer 102, some may osmose into the blood compartment and bedelivered to the patient, but the majority of it will be carried alongthe outsides of the dialyzer membranes and be flushed to drain 60. Thusthe patient will see very little of the original citric acid.

After filling or priming step 218, a second patient performs a secondtreatment at step 204. Method 200 repeats steps 204 to 218 until noadditional treatments remain. At step 216, if no treatments remain,method 200 proceeds to step 220, where at the end of the day, the system10 a or 10 b may be left wet or dry. If wet, logic implementer 20 mayfill the dialysis fluid circuit 30 with purified water to compensate forthe limited drain. The next day will begin with a filling or primingstep to further reduce or eliminate citric acid as described at step218. If dry, logic implementer 20 may drain dialysis fluid circuit 30completely, removing all citric acid (which may be done alternatively atstep 214 instead of a partial drain if it is known at that time that nofurther treatments will be performed).

Method 200 ends at step 222.

Importantly, method 200 does not include a rinse cycle after circulationstep 212. Instead, method 200 moves directly to a drain cycle in step214, which may even be a limited drain cycle. Thus, a significant amountof time between treatments is saved. As described herein, the skippingof the rinse cycle is enabled through the use of a physiologicalcleaning, disinfecting, and/or decalcifying cleaning agent, such acitric acid. In one embodiment, as illustrated in FIGS. 1A and 1B, aconnector 94 a associated with the source 86, 90 of physiologicalcleaning, disinfecting, and/or decalcifying substance and a matingconnector 94 b associated with machines 12 of systems 10 a and 10 b arekeyed or configured so that machine 12 may only accept a certain type orbrand of cleaning agent, namely, a physiologically safe cleaning,disinfecting, and/or decalcifying substance. Here, if a user tries toplug a different type or brand of cleaning agent, e.g., which is notphysiologically safe, into connector 94 b, connection will be prevented.Such keying and/or configuring of connectors 94 a and 94 b ensures thatthe cleaning agent connected to machine 12 is appropriate for skippingthe disinfecting rinse and the running the limited drain.

Moreover, besides the keying or configuring of connectors 94 a and 94 b,it is contemplated to package the source 86, 90 of physiologicalcleaning, disinfecting, and/or decalcifying substance so as to ensurethat it is a single use package. For example, the package may have afilm that is permanently punctured or a tab that is permanently removedto show that it is to be used once and then discarded. Suitable writingsand indicia may also mark the package or source 86, 90 as being singleuse. In this way, a user is dissuaded from refilling the package with anon-physiological cleaning, disinfecting, and/or decalcifying cleaningagent. Alternatively or additionally to the puncture films, removabletabs and suitable indicia, the packaging for sources 86, 90 may have aone-way valve or flap that physically prevents a user from reloading thesource with a non-physiologically safe cleaning agent.

Alternatively, or in addition to the use of mated keyed connectors 94 aand 94 b and/or the single use packages or sources 86, 90, physiologicalcleaning, disinfecting, and/or decalcifying substance may be providedwith a marking 85, such as a barcode, 3D barcode, radio frequencyidentifier (“RFID”) chip or any type of indicia that may be read by acorresponding scanner, reader, RFID reader, or camera 15. In theillustrated embodiment, scanner, reader, RFID reader, or camera 15 isprovided with user interface 14 of machine 12, and thus communicateswith one or more processor 16 and memory 18 of logic implementer 20.Scanner, reader, RFID reader, or camera 15 may be provided at the end ofa cord or be flush mounted to machine 12.

One or more processor 16 of logic implementer is programmed duringtreatment setup to read marking 85 on source 86, 90 at scanner, reader,RFID reader, or camera 15 prior to the connection of the source tomachine 12 of system 10 a or 10 b. That way, machine 12 knows if thecleaning agent is physiologically safe or not. If not, logic implementer20 is programmed to run a standard treatment sequence, including a freshwater rinse after disinfection and a full drain after the rinse. Ifscanner, reader or camera 15 reads that the source 86, 90 isphysiologically safe, logic implementer determines that machine 12 mayinstead run the shortened treatment sequence of method 200. Logicimplementer 20 may cause user interface 14 to display a suitable audio,visual or audiovisual message asking for confirmation of the shortenedsequence, such as, “CleanCart® cartridge detected, please [confirm] or[cancel] no rinse and limited drain.” The user may then press [confirm]or [cancel] to accept or reject the shorter transition betweentreatments. In an embodiment, no rinse and limited drain are enabledonly when scanner, reader, RFID reader, or camera 15 detects that thesource 86, 90 is physiologically safe.

Further additionally or alternatively to the use of mated keyedconnectors 94 a and 94 b, single use packages, and/or markings 85 andscanner, reader, RFID reader, or camera 15, machine 12 (i) just upstreamor downstream of valve 92 f in FIG. 1A or (ii) just downstream ofconnector 94 b in FIG. 1B may place a pH detector and/or conductivitysensor (not illustrated) for detecting the pH and/or conductivity of thecleaning agent just as it begins to enter dialysis fluid circuit 30. Thereadings from pH detector and/or conductivity sensor are sent to logicimplementer 20. Logic implementer 20 may be programmed to, for example,use the readings to determine that the source 86, 90 is (i) notphysiologically safe and run a standard disinfectant rinse and drain,notifying the user of same via user interface 14 or (ii) physiologicallysafe and run method 200 with no disinfectant rinse and limited drain,notifying the user of same via user interface 14. Alternatively, thereadings are used to confirm that source 86, 90 is physiologically safeafter being told so by the user or determining so via scanner, reader,RFID reader, or camera 15.

Referring now to FIG. 5, an example timeline summarizing the timing andresults of method 200 is illustrated. All values used in connection withFIG. 5 are example values and are not meant to be limiting or necessary.At time zero, treatment has already been performed and the used dialysisfluid has been drained completely from dialysis fluid circuit 30. Attime T1 (end of step 208), e.g., at 1 or 2 minutes, dialysis fluidcircuit 30 is filled with purified water and citric acid, e.g. 32 grams.At time T2 (end of step 210) the, e.g., 32 grams of citric acid remainsand the mixture has been heated over about ten minutes. At time T3 (endof step 212), the disinfecting mixture has been circulated in a cleaningmanner for about one (1) to thirty (30) minutes. At time T4 (end of step214) a limited drain has been performed for about one (1) to two (2)minutes, bringing the citric acid down to, e.g., 3 grams. In anembodiment, at least 85% of the citric acid has been removed by time T4.At time T5 (end of step 218) a system 10 filling sequence with exchangesis performed, flushing virtually all the remaining citric acid, e.g.,bringing the citric acid level down to 0.3 gram or below.

In another example, if at time T4 (at the end of limited drain), thecitric acid level is only 0.5 gram, the filling sequence with exchangesmay bring the citric acid level down to 0.18 gram. Here, 0.32 gram orone percent of the original 32 grams of citric acid or physiologicalcleaning, disinfecting, and/or decalcifying substance is removed. Asdiscussed above, it is contemplated to remove at least one percent ofthe original citric acid or other physiological cleaning, disinfecting,and/or decalcifying substance.

The total time range from time T0 to time T4 is from thirteen minutes(1+10+1+1) to forty-four minutes (2+10+30+2).

As discussed above, patients using citrate anticoagulant tolerate six(6) to twelve (12) grams of citrate per hour. Method 200 removes citricacid to a much lower level. Thus some steps of method 200 may be reducedor eliminated. For example, cleaning or circulating step 212 may beshortened or eliminated if enough citric acid may be removed in steps214 and 216. Or, the limited drain step 214 may be shortened oreliminated if enough citric acid may be removed in steps 212 and 216.Or, the priming exchanges may be shortened or eliminated if enoughcitric acid may be removed in steps 212 and 214. Any of the alternativeslisted may be combined with a varying amount of initially suppliedcitric acid, e.g., from twenty (20) to fifty (50) grams, to achieve adesired amount of disinfection.

The present disclosure is also not limited to citric acid and applies toother physiological cleaning, disinfecting, and/or decalcifyingsubstance, which may be added from a source to purified water from itssource 22 to form a mixture, and which may be circulated within thedialysis fluid circuit using the dialysis fluid pump to disinfect and/orclean and/or decalcify the dialysis fluid circuit after a firsttreatment, and where the this disinfection procedure does not require asubsequent rinse procedure. The physiological cleaning, disinfecting,and/or decalcifying substance may be an acid, such as citric acid,lactic acid, malic acid, acetic acid, and gluconic acid, or anycombination thereof. The substance may also be an acid, such as any oneor more above, in combination with another physiologically safesubstance, such as salts and/or sugars.

Note, in order to be able to cool the dialysis machine of system 10,logic implementer 20 may alternatively regulate the dialysis fluidtemperature to some temperature lower than the normally required 35° C.to 38° C., for example, to 25° C. to 30° C. to cool the machine withstart-up solution or priming solution during filling or online priming.

Referring now to FIGS. 6 and 7, graphs illustrating that residual citricacid at the beginning of filling or priming will not negatively impactthe creation of dialysis fluid are illustrated. In particular, FIGS. 6and 7 show the impact of the residual citric acid on the pH of the newlyformed dialysis fluid. FIG. 6 illustrates pH recovery for a bicarbonatetreatment (much more common), while FIG. 7 illustrates pH recovery foran acetate treatment. For bicarbonate treatment in FIG. 6, the dialysisfluid never becomes acidic and indeed it takes nine minutes for the pHto drop to neutral to reach a “green fluid path”, meaning treatment mayproceed. As mentioned above, citrate and citric acid are not exactly thesame. But when citric acid meats bicarbonate, the citric acid reacts andbecomes citrate, leaving an initial dip in bicarbonate. For acetatetreatment in FIG. 7, the dialysis fluid becomes acidic for the firstfour minutes but reaches the “green fluid path” (treatment may proceed)at around six minutes. In both cases, “green fluid path”, or ready fordelivery is reached in a reasonable time period. Also, in both cases theready to be delivered point or stage is reached after a time when citricacid impact is still measurable.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications may be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

The invention is claimed as follows:
 1. A renal failure therapy systemcomprising: a dialysis fluid circuit including a dialysis fluid pump; asource of physiological cleaning, disinfecting, and/or decalcifyingsubstance in fluid communication with the dialysis fluid circuit; asource of purified water in fluid communication with the dialysis fluidcircuit; and a logic implementer in operable communication with thedialysis fluid pump, wherein the logic implementer is programmed suchthat the system is configured to: cause the physiological cleaning,disinfecting, and/or decalcifying substance to be added from its sourceto purified water from the purified water source to form a mixture,circulate the mixture within the dialysis fluid circuit using thedialysis fluid pump to at least one of clean, disinfect, or decalcify atleast a portion of the dialysis fluid circuit without a subsequent rinseafter circulating and moving directly to a drain sequence, cause aportion of the mixture to be drained in the drain sequence, whereindraining a portion of the mixture from the dialysis fluid circuitincludes trapping air in the dialysis fluid circuit, and cause a fillingprocedure for a second treatment to begin with a portion of the mixtureremaining in the dialysis fluid circuit, wherein the filling procedurereduces the remaining mixture to a lower level and removes a portion ofthe remaining mixture to drain.
 2. The renal failure therapy system ofclaim 1, wherein the physiological cleaning, disinfecting, and/ordecalcifying substance includes an acid.
 3. The renal failure therapysystem of claim 2, wherein the acid is at least partially citric acid.4. The renal failure therapy system of claim 1, wherein thephysiological cleaning, disinfecting, and/or decalcifying substanceincludes citric acid in combination with a physiologically safesubstance.
 5. The renal failure therapy system of claim 1, wherein thethreshold amount is one percent of an amount of physiological cleaning,disinfecting, and/or decalcifying substance added from its source topurified water to form the mixture.
 6. The renal failure therapy systemof claim 1, wherein the filling procedure involves an introduction of abicarbonate substance from a source that neutralizes the physiologicalcleaning, disinfecting, and/or decalcifying substance.
 7. The renalfailure therapy system of claim 1, wherein the filling procedure removesat least one percent of an original amount of the physiologicalcleaning, disinfecting, and/or decalcifying substance.
 8. The renalfailure therapy system of claim 1, which includes a heater, the logicimplementer programmed to control the heater such that a filling fluidis introduced to the dialysis fluid circuit during the filling procedureat a temperature below 35° C.
 9. The renal failure therapy system ofclaim 8, wherein the logic implementer is further programmed to causethe heater to heat the mixture while at least one of cleaning,disinfecting, or decalcifying the at least a portion of the dialysisfluid circuit.
 10. The renal failure therapy system according to claim1, which includes at least one of (i) a keyed connector for the sourceof physiological cleaning, disinfecting, and/or decalcifying substanceand a mating keyed connector for dialysis fluid circuit, or (ii) amarking associated with the source of physiological cleaning,disinfecting, and/or decalcifying substance and a scanner, reader, RFIDreader, or camera in communication with logic implementer for readingthe marking, upon which the logic implementer can allow or confirm thecirculating of the mixture without the subsequent rinse.
 11. The renalfailure therapy system according claim 1, wherein the dialysis fluidcircuit includes a disinfection recirculation loop and an air separationchamber located within the loop, the air separation chamber increasingat least one of a flowrate and a heating efficiency of the physiologicalcleaning, disinfecting, and/or decalcifying substance flowing within thedisinfection recirculation loop.
 12. The renal failure therapy systemaccording claim 1, wherein the logic implementer is further programmedto: cause purified water to flow from the source of purified water to adrain, the purified water flow causes remaining pockets of thephysiological cleaning, disinfecting, and/or decalcifying substance andair to be flushed to drain; and add a concentrate to the purified waterto form dialysis fluid, wherein forming the dialysis fluid causes the atleast a portion of the remaining part of the mixture to be removed todrain.
 13. A renal failure therapy machine operable with a source ofphysiological cleaning, disinfecting, and/or decalcifying substance anda source of purified water, the machine comprising: a dialysis fluidcircuit including a dialysis fluid pump, the dialysis fluid circuitconfigured to pump from the physiological cleaning, disinfecting, and/ordecalcifying substance source and the purified water source; and a logicimplementer in operable communication with the dialysis fluid pump, thelogic implementer programmed such that the machine is configured tocause: the physiological cleaning, disinfecting, and/or decalcifyingsubstance from its source to be added to purified water from thepurified water source to form a mixture and to circulate the mixturewithin the dialysis fluid circuit using the dialysis fluid pump to atleast one of clean, disinfect or decalcify at least a portion of thedialysis fluid circuit after a first treatment, a portion of the mixtureto be drained in a drain sequence that begins directly after circulationof the mixture and without a separate rinsing sequence in between,wherein the drain sequence includes trapping air in the dialysis fluidcircuit while draining the portion of the mixture, and a fillingprocedure for a second treatment to begin directly after the drainsequence, and without a separate rinsing sequence in between, with themixture remaining in the dialysis fluid circuit, the filling procedurerelied upon to reduce the mixture remaining to a lower level.
 14. Therenal failure therapy machine of claim 13, wherein the logic implementeris programmed to circulate the mixture within the dialysis fluid circuitfrom about one to about thirty minutes.
 15. The renal failure therapymachine of claim 13, wherein, during the filling procedure, at least onepercent of an original amount of the physiological cleaning,disinfecting, and/or decalcifying substance is removed.
 16. The renalfailure therapy machine according to claim 13, wherein, during thefilling procedure, a bicarbonate substance from a source is provided,which neutralizes the physiological cleaning, disinfecting, and/ordecalcifying substance.
 17. The renal failure therapy machine accordingto claim 13, wherein the drained portion of the mixture is a firstportion, and wherein the logic implementer is further programmed to moveto the second treatment including performing a filling procedure thatdrains a second portion of the mixture.